We compared the upper 10% of consistently very happy people with average and very unhappy people. The very happy people were highly social, and had stronger romantic and other social relationships than less happy groups. They were more extroverted, more agreeable, and less neurotic, and scored lower on several psychopathology scales of the Minnesota Multiphasic Personality Inventory.

What happens when you take an introvert and make them act like an extrovert? They get happier:

Results replicated and extended past findings suggesting that acting extroverted produces hedonic benefits regardless of disposition. Positive affect increased and negative affect did not, even for participants acting out of character… We conclude that dispositional introverts may indeed benefit from acting extroverted more often…

That’s some pretty eye-opening evidence. (But, to be fair, those chatty extroverts are much better at PR, so let’s reserve judgment for the time being.)

Other research shows there may be a connection between extraversion and intelligence but that’s been debated. On the other hand, what predicts college grades better than IQ? Being an introvert.

At the university level, introversion predicts academic performance better than cognitive ability.One study tested 141 college students’ knowledge of twenty different subjects, from art to astronomy to statistics, and found that introverts knew more than the extroverts about every single one of them. Introverts receive disproportionate numbers of graduate degrees, National Merit Scholarship finalist positions, and Phi Beta Kappa keys. They outperform extroverts on the Watson-Glaser Critical Thinking Appraisal test, an assessment of critical thinking widely used by businesses for hiring and promotion. They’ve been shown to excel at something psychologists call “insightful problem solving.”

Need a top expert in a field? Might not want to pick that outgoing fellow.

Teens who are too gregarious to spend time alone often fail to cultivate their talents “because practicing music or studying math requires a solitude they dread.” …Ericsson and his cohorts found similar effects of solitude when they studied other kinds of expert performers. “Serious study alone” is the strongest predictor of skill for tournament-rated chess players… College students who tend to study alone learn more over time than those who work in groups. Even elite athletes in team sports often spend unusual amounts of time in solitary practice.

What about more social areas of expertise, like leadership? It definitely gets more complex. Extroverts are better leaders of passive employees, introverts shine with proactive workers:

…although extroverted leadership enhances group performance when employees are passive, this effect reverses when employees are proactive, because extroverted leaders are less receptive to proactivity.

Me? I remember taking a personality test in college and blowing away the instructors with my introversion score. They were curious to learn more about me but, unsurprisingly, I had little interest in talking with them.